Oscillation circuits



Aug. 27, 1929. w. KUMMERER OSCILLATION CIRCUITS Filed Aug. 18, 1925 J! 4IF INVENTOR mm 0mm ATTORNEY Patented Aug. 27, 1929.

UNHEE) STATES WILHELM KUMMERER, OF BERLIN, GERMANY, ASSIGNOR T0 RADIOCORPORATION OF AMERICA, A CORPORATION OF DELAVIAR-E.

OSCILLATION CIRCUITS.

Application filed August 18, 1825, Serial No. 50,982, and in GermanyOctober 1, 1924.

It is well known that the anode alternating current as well as the gridalternating current potential of oscillation tubes must have verydefinite values at a given anode direct current potential, if theoscillation tube is to operate under optimum conditions. However, thesevalues are unvaried within rather wide limits as the wave-length ischanged. The consequence is that the ratio between anode alternatingcurrent potential and grid alternating current potential should remaininvariably the same as the wavelength undergoes changes.

' An object of the present invention is to maintain the proper gridpotential automaticall Other objects will be apparent from the followingspecification and drawings in which Fig. 1 represents diagrammaticallythe fundamental connections of a tube transmitter involved in thisinvention.

Fig. 2 shows a slightly different set of connections embodying thisinvention.

Fig. 8 shows an embodiment of this invention as applied to a modifiedcircuit.

Referring more particularly to the figures, in Fig. 1 there isdiagrammatically shown the connections of a tube transmitter in which ais the oscillation tube, 5 the coil of the oscillation circuit which isprovided with several taps 79 for the connection of the anode, and tapsQ for the wave length adjustment; 0 is a variable condenser whose valueis changed either continuously or by steps, and which is intended forwave-length adjustment, (Z the anode blocking condenser, e the anodechoke coil designed to prevent a shortcircuit by way of the directcurrent source It is customary to couple the back coupling coil for thegrid alternating current potential to the oscillation circuit coilloosely. But this arrangement involves the drawback that upon everychange in wave length the degree of the coupling of necessity must bevaried and set in order that the proper grid potential may be obtained,unless the tube is to be operated with a more or less incorrect gridpotential. However, in order that the proper grid potential may alwaysbe obtained automatically, so to speak, it is also customary to dividethe anode alternating current potential between points 00 and y eitherby inductive or capacitive means in the manner of a potentiometerconnection.

However, if this voltage divider element is passed only by a feeblecurrent of high fre quency, the ratio of potential division is changedowing to the load by the grid, with the consequence that on varying thewave nating current potential is stepped down by the aid of atransformer of fixed coupling ratio to the value suited for the grid. Asshown in Fig. 1, g is the primary winding of the coupling transformerwhich is connected at points 00 and 11 and h is the secondary winding towhich the grid 71 is united.

Another form of construction of the idea underlying the presentinvention consists in that the grid coupling transformer serves at thesame time as the anode choker, as shown in Fig. 2. It can readily beseen that at the grid choker e the full anode alternating currentpotential is obtained between points a and o, for the direct currentsource 7 constitutes an almost complete short-circuit for the highfrequency current. Apart from a notable simplification, this arrangementfurthermore oifers the great advantage that parallel to theoscillation-circuit coil or variometer Z) there no longer are connectedboth the anode choking coil 6 and the primary winding of the couplingtransformer g. This is of utmost advantage in order to insure a largerange of variation. for the variometer.

The said coupling transformer moreover may be used for the object ofchanging the amplitude of the potential alternations of the oscillationcircuit. For instance, in the case of transmitters worked at a highanode direct current potential, the alternating cur rent potential ofthe oscillation circuit may be accommodated to be a satisfactory valueto accompany this high anode potential. An embodiment of this scheme isillustrated diagrammatically in Fig. 3 where g and 9 stand for the twoprimary-winding halves of the transformer of constant coupling ratio,While it again denotes the secondary winding to which the grid isconnected. By such a transformer arrangement the alternating potentialamplitude applied to the output circuit of the oscillator may differfrom the potential amplitude applied to the direct current branch of theoscillator, to Which branch the grid or control electrode circuit iscoupled for oscillation.

Having thus described my invention, What I claim is 2- 1. An oscillationgenerator comprising a valve having an anode, a cathode, and a control.electrode, an input anode-cathode circuit including a source of directcurrent, an output anode-cathode circuit including a resonant circuit,means to couple said input and output circuits including a transformerof desired ratio, and a control electrode-cathode circuit includingmeans coupled to the anodecathode circuits.

2. An oscillation generator comprising a valve having an anode, acathode, and a control electrode, an input anode-cathode c1rcu1t 7including a source of direct current, an output anode cathode circuitincluding a res onant circuit, means to couple said input and outputcircuits including a transformer of desired ratio, and a controlelectrode-cathode circuit including an additional transformer coilcoupled to the transformer of the anode-cathode circuits.

3. A vacuum tube oscillation generator comprising a vacuum tube, ananode-cathode circuit having parallel connected alternating current anddirect current branches, a control electrode-cathode circuit coupled tothe direct current branch of the anode-cathode circuit, and atransformer to couple the direct current and alternating currentbranches of the anodecathode circuit in desired ratio.

WVILHELM KUMMERER.

